Optimistik - If you don't tell him why, he can't change.
He needs to start being a man. He seems completely disinterested in your body, and that will have a profound affect on your self-confidence. It will also probably be picked up by your children, over time - I should think that it is visible in non-sexual tones, too.
You need to talk to him, and tell him that while he is allowed to have preferences, (if he really dislikes oral sex, that could be it, for example) but he cannot just decide that he prefers not to touch you at all. He's treating you like you are dirty, but he's quite happy to have sex with you when it suits him.
If it was me, I'd buy a sex toy and suggest that he learns to use that. It doesn't involve his hands or tongue, so he can have no issue with it. I bet he'd come up with an excuse then, too - he just doesn't want, or feel the need, to make you happy.
Don't waste your life waiting for him to change. You need to have an honest conversation and tell him to ship up or ship out.